基于微孔充填模型的页岩储层吸附动力学特征分析

摘要

微孔填充是吸附质分子在吸附剂纳微孔隙中、较高平衡压力下表现出来的一种吸附特征，以此为基础发展起来的热力学理论在确定吸附剂微观结构及吸附性能研究方面起到了巨大推动作用。基于此，该文重点探讨了甲烷在页岩中吸附时填充率θ、特征能量E、特征系数n、微分吸附功A、吸附热Q、吸附焓ΔH及吸附熵ΔS的变化关系。结果表明：特征系数n取1较为适当；温度升高特征能量E值略降，3组样品E值范围4.14~5.63 kJ/mol；随着θ的不断增加，A，Q，｜ΔH｜及｜ΔS｜等参数值逐渐降低，各能量参数随吸附进行而发生较为规律的变化，无突变。结果认为，热力学参数一定程度上代表了TOC及Ro等参数的综合效应，受单一因素干扰性不强。将计算的Q及ΔS等热力学参数与四川盆地志留系龙马溪组页岩的相应参数进行了对比，进一步表明四川盆地该套龙马溪组页岩具有巨大的页岩气勘探和开发潜力。%Micro-pore filling is an adsorption behavior that usually happens in micropores and high equilibrium pressure conditions, the thermodynamic theory based on this theory played a great role in determining the microscopic structures and adsorption properties. In this paper, we mainly discuss the relationship of filling rateθ, character energy E, character coefficience n, differential adsorption work A, the adsorption heat Q, the adsorption enthalpyΔH and the adsorption entropyΔS for methan. The results show that 1) n=1 is appropriate;2) the value of E decreases with raising temperatures;3) E is among 4.14~5.63 kJ/mol;with the increase ofθvalue, Q,ΔH, andΔS decrease. These parameters change continuously and do not show sudden change. To some extent, the thermodynamic parameters can represent the comprehensive effects of parameters such as TOC and Ro. Comparison of the calculated parameters in this paper with the adsorption energy value of the Longmaxi shale in Sichuan basin shows that this set of shale in China has huge exploration and development potential.